Thursday April 6, 2006
Dear Dr. Mady: My dentist is recommending that I get crowns placed on a couple of my teeth. What exactly are crowns and what is the reason why some people need them?-Sylvio in Puce
Dear Sylvio: A crown is a tooth shaped covering or “cap” that is placed over a tooth to restore it to it’s original size and shape, to strengthen it and to improve it’s appearance. When completed and cemented in place, a crown completely covers the entire visible portion of your tooth that is above the gum line.
There are many reasons why crowns are needed on teeth and why your dentist may recommend them. Sometimes crowns are used to strengthen a weak tooth or one that is cracked. This tooth may already even be broken or moderately worn. Crowns are also extremely beneficial when a tooth has a very large filling in it, not a lot of natural tooth structure remaining and when it is structurally compromised.
You may have a need for a crown if your teeth are misshaped or severely discolored, or to be placed on top of an dental implant. The most common need for a crown that even outweighs cosmetics is when a tooth has had a root canal (endodontic treatment), especially on posterior or back teeth. Endodontically treated teeth become brittle over time due to the loss of nerve and blood supply and are very susceptible to fracture. When a crown is placed it can actually strengthen the tooth and is an excellent preventative measure.
Preparing your tooth or teeth for a crown usually requires two dental visits. At the first appointment, your crown prep will be completed using a local anesthetic, a final impression or mould will be taken and a temporary crown will be placed. The second appointment is when you will get your crown(s) delivered or placed. They are usually cemented permanently with a dental cement.
While waiting for your permanent crown to be fabricated, you have to be cautious with the temporary crown. Avoid sticky foods that can pull the crown off and try not to floss aggressively around the temporary. These are usually fabricated from acrylic and are not meant to be on “too tight”. If the temporary crown does come off, you must notify your dentist immediately because if it stays off, the prepped tooth can move or hyper-erupt and then there is risk that the permanent crown will not fit. Also avoid hard foods with your temporary and try to chew in other areas of your mouth.
Permanent crowns can be made of metal, all porcelain ceramic, or a combination of porcelain fused to metal. The strongest ones are the metal and porcelain fused to metal, but the all-ceramic type is the most esthetically pleasing. The metal crowns are usually made from gold but the porcelain crowns can be color matched to the adjacent teeth. Metal crowns require removal of less tooth structure as opposed to the other types. Pocelain can wear the opposing teeth more than metal, and fracture easier, but most patients shy away from metal due to the “look” of it.
All-ceramic crowns are the best choice for anterior or front tooth restorations because they provide the best natural color match of all crown types. They are also more suitable for individuals with metal allergies.
The newly crowned tooth may be sensitive immediately after the anesthetic wears out. This may occur after the prep and even after the permanent cementation. If the tooth in question still contains a live nerve, you may experience some hot and cold sensitivity. This usually subsides quickly but if it does not or if it worsens, let your dentist know.
Dental crowns usually last between five and fifteen years, but may last longer. The life span depends on several variables including but not limited to oral hygiene practices, oral habits (like chewing on things), bruxism (grinding) and clenching.
Crowned teeth do not require any special care, but many believe that a crowned tooth can not get a cavity. This is completely false and if good oral hygiene is not practiced, the tooth structure that supports the crown can decay and often without you knowing it before it is too late. Therefore, after your crowns are placed, continue brushing at least twice a day, flossing once a day and keep your regular check-up and cleaning appointments with your dentist.
If you need any other information or have any dental questions, please e-mail Dr. Mady at firstname.lastname@example.org
This column is reprinted with the permission of the author and The Windsor Star. "Ask the Dentist" is written by Windsor dentist (and ECDS member), Dr. David Mady Jr.. The column appears the first Thursday of each month in the Windsor Star. Readers with questions can write to "Ask The Dentist", c/o The Windsor Star, 167 Ferry St., Windsor Ontario, N9A 4M5